Device and method of classifying emulsion and method of demulsifying emulsion

ABSTRACT

A classifying apparatus ( 1 ) has a flow path (structure) through which an emulsion flows. The flow path is provided between at least two plates (upper plate ( 2 ), lower plate ( 4 )) that are separated by a distance smaller than the largest diameter of a liquid droplet included in the emulsion. Emulsion is fed from a supply port ( 5 ) provided in the upper plate ( 2 ) and can be classified by passing it in the flow path.

TECHNICAL FIELD

The present invention relates to a classifying apparatus and aclassifying method of obtaining only tiny liquid droplets by an emulsionclassification performed in such a manner that large liquid particles(liquid droplets) in an emulsion containing liquid droplets withdifferent particle diameters (droplet diameters) are made coalesced witheach other. More specifically, the present invention relates to aclassifying apparatus and a classifying method capable of demulsifyingliquid droplets to a continuous phase by classifying the emulsion toobtain liquid droplets having so small diameter that cannot be visuallyobserved.

BACKGROUND ART

A liquid-liquid extraction performed in such a manner that after auseful substance dissolved in an aqueous phase is extracted to an oilphase, or after a salt and other substance dissolved in an oil phase isextracted to an aqueous phase, the useful substance and the salt areextracted by separation into the aqueous phase and the oil phase, is anoperation widely adopted in the industries such as environmentalindustry involving a waste water treatment, pharmaceutical andagricultural chemical industries, chemical industry, and food industry.The liquid-liquid extraction is, for example, an operation oftransferring a useful substance and salt dissolved in an aqueous phaseor an oil phase into other liquid phase.

For enhancement of efficiency in the liquid-liquid extraction, generallyperformed is a phase-separation after another liquid droplets are madedispersed in one liquid phase by agitation or the like for production ofan emulsion. That is, increase in an area of an interface (interfacearea) between mutually different phases enhances efficiency inliquid-liquid extraction. Specifically, it is generally known thatliquid droplets having a smaller diameter contained in the emulsionincrease an interface area between the different two phases, whichbrings a prompt extraction of a useful substance and salt (For example,non-patent document 1).

By the way, there has been a demand for a more prompt liquid-liquidextraction, which is required to address the problems such asdecomposition of a useful substance by reaction with one phase anddecomposition of a useful substance in temperatures necessary for theextraction. Recently, non-patent document 2 has suggested a method ofpromptly extracting a useful substance (phenol) from an aqueous phase toan oil phase (dodecane phase) with the use of an emulsion havingsubmicron-diameter liquid droplets, generated by using an apparatustermed as “micromixer”.

However, for example, in the emulsion generated by the method disclosedin the non-patent document 2 and an emulsion containing an emulsifier,liquid droplets contained in these emulsions exist stable withoutcoalescing with one another. Therefore, these emulsions may keep stablefor a long time. Thus, when such a stable emulsion is used, i.e. whendemulsification is not readily performed, it takes long time to separatethe emulsion into two liquids even though the extraction is performedpromptly.

For example, patent documents 1 and 2 disclose a method for solving sucha problem.

Specifically, in the method disclosed in patent documents 1 and 2, anemulsion is separated into oil and water in such a manner that theemulsion is made passed through a filter realized by a textile having avery small hole diameter. In the method disclosed in the patentdocuments 1 and 2, the filter collects liquid droplets contained in theemulsion as the emulsion passes through the filter. Then, when theseliquid droplets join together to form a large droplet, the large dropletis discharged out of the filter.

[Non-patent document 1]

“Theory and Calculation of the Chemical Machine”, 2nd ed., p. 288,Saburoh Kamei, Sangyotosho Corp. (1975)

[Non-patent document 2]

Preprint G216 of 35th Autumn Annual Meeting by the Society of ChemicalEngineers, Japan, Maki, Mae et al. (2002)

[Patent document 1]

Japanese Patent No. 2572068 (registered on Oct. 24, 1996)

[Patent document 2]

Japanese Laid-Open Patent Application No. 2000/288303 (Published on Oct.17, 2000)

By the way, in the arrangements disclosed in the patent documents 1 and2, separation of an emulsion into oil and water is performed using thefilters. These filters, which are realized by textiles, have grains ofrandom opening diameters. Therefore, when a liquid droplet smaller thanthe opening diameters flows through the filter in a spot havingrelatively large opening diameter, for example, the liquid dropletpasses straight through the relatively large opening of the filterwithout coalescing with other liquid droplet. In other words, liquiddroplets contained in the emulsion cannot coalesce with each otherdepending upon spots of the flow path through which an emulsion passes.

Thus, the arrangement of the patent document 1 cannot adjust openingdiameters of the flow path through which liquid droplets contained inthe emulsion pass in the filter to make uniform opening diameters, thusmaking impossible to classify liquid droplets passing though the filterso as to obtain droplets having a desired diameter or smaller.

Further, the arrangements disclosed in the patent documents 1 and 2cannot adjust the flow path of liquid droplets contained in theemulsion. This needs to precisely adjust a flow rate of the emulsion tobe passed through the flow path, for realization of an efficientseparation into oil and water. In other words, in the arrangementsdisclosed in the patent documents 1 and 2, liquid droplets contained inthe emulsion do not coalesce with each other, when a flow rate of theemulsion is fast or slow, and do not form one continuous phase. Thiscauses the emulsion to be discharged without demulsified.

Still further, the arrangements disclosed in the patent documents 1 and2 cannot provide uniform opening diameters of the filter grains. Inaddition, it becomes more difficult to make a uniform distribution ofthe opening diameters as the opening diameter of the filter grainsbecomes smaller. For example, it is very difficult to classify anemulsion having extremely-small-diameter liquid droplets generated withthe use of the micromixer disclosed in the non-patent document 2.

Besides, in a case where the filters disclosed in the patent documents 1and 2 are used, the filters gradually swell due to a long-timeseparation into oil and water. This increases a liquid passageresistance of the filters. Thus, it is very difficult for the filters toprovide a constant oil-and-water separation performance all the time.

DISCLOSURE OF INVENTION

The present invention has been attained in view of the above problems,and an object thereof is to provide a classifying apparatus and aclassifying method for more easily classifying liquid droplets containedin an emulsion to obtain liquid droplets having a desired diameter orsmaller.

A classifying apparatus according to the present invention, in order tosolve the above problems, has a flow path having a desired depth orwidth smaller than the largest diameter in liquid droplets contained inan emulsion, wherein at least a part of the flow path is made of amaterial having affinity with the liquid droplets.

When the emulsion passes through the flow path, the liquid dropletslarger than a desired depth or width (hereinafter referred to as thesmallest length) smaller than the largest diameter in liquid dropletscontained in the emulsion in the flow path, among the liquid dropletscontained in the emulsion, deform so as to fit in the smallest length,and the liquid droplets are wetted on a material having an affinity withthe liquid droplets (hereinafter it may be referred to as dropletaffinity material). Then, when the emulsion is continuously supplied tothe flow path, there occurs a difference in relative velocity between adispersion medium flowing through the flow path and the liquid droplets.This is because the liquid droplets are wetted on the droplet affinitymaterial, and the dispersion medium resists being wetted on the dropletaffinity material. Then, if liquid droplets on the upstream of the flowpath are smaller in size than liquid droplets on the downstream of theflow path, the liquid droplets on the upstream catch up with the liquiddroplets on the downstream. At this moment, the liquid droplets arewetted on the droplet affinity material, and therefore coalesce withother liquid droplets by acting to decrease their surface areas fortheir stabilities. This causes coalescence of the liquid droplets largerthan the smallest length of the flow path to coalesce by passing throughthe flow path. On the other hand, liquid droplets smaller than thesmallest length of the flow path pass without being wetted on thedroplet affinity material, and therefore do not coalesce with otherliquid droplets. Thus, the smaller liquid droplets keep their shape evenafter having passed through the flow path.

According to the above arrangement, the liquid droplets larger than thesmallest length can be formed to a larger liquid droplet (made coalescedwith each other) in such a manner that the liquid droplets contained inthe emulsion are caused to pass through the flow path having thesmallest length, more specifically, the liquid droplets contained in theemulsion are caused to pass in a wetted state through the flow path.With this, the liquid droplets can coalesce with each other to form acontinuous phase, and then separate from the emulsion. Further, theliquid droplets smaller than the smallest length keep as they are.

That is, with the above arrangement, it is possible to reliably flow theliquid droplets contained in the emulsion through the flow path havingthe smallest length. Thus, it is possible to classify the liquiddroplets contained in the emulsion so as to obtain liquid dropletshaving a desired diameter or smaller.

In order to solve the above problems, a method for classifying emulsionof the present invention includes passing emulsion through a flow pathin an apparatus for classifying emulsion, wherein the apparatus has aflow path having a desired depth or width smaller than the largestdiameter in liquid droplets contained in the emulsion, and wherein atleast a part of walls forming the flow path is made of a material havingaffinity with the liquid droplets.

According to the above arrangement, the liquid droplets larger than thesmallest length can be formed to a larger liquid droplet (made coalescedwith each other) in such a manner that the liquid droplets contained inthe emulsion are caused to pass through the flow path having thesmallest length, more specifically, the liquid droplets contained in theemulsion are caused to pass in a wetted state through the flow path.Further, liquid droplets smaller than the smallest length keep as theyare.

That is, with the above arrangement, it is possible to reliably flow theliquid droplets contained in the emulsion through the flow path havingthe smallest length. Therefore, the liquid droplets larger than thesmallest length can coalesce with each other to form a continuous phase,and then separate from the emulsion. Thus, it is possible to classifythe liquid droplets contained in the emulsion so as to obtain liquiddroplets having a desired diameter or smaller.

A method for demulsifying emulsion of the present invention includespassing emulsion through a flow path in an apparatus for classifyingemulsion and phase-separating the passed liquid, wherein the apparatushas a flow path having a desired depth or width smaller than the largestdiameter in liquid droplets contained in the emulsion, and wherein atleast a part of walls forming the flow path is made of a material havingaffinity with the liquid droplets.

According to the above arrangement, the liquid droplets larger than thesmallest length can be formed to a larger liquid droplet (made coalescedwith each other) in such a manner that the liquid droplets contained inthe emulsion are caused to pass through the flow path having thesmallest length, more specifically, the liquid droplets contained in theemulsion are caused to pass in a wetted state through the flow path.Thus, it is possible to easily phase-separate the emulsion fordemulsification.

The following description will sufficiently clarify further objects,characteristics, and excellent points of the present invention. Further,advantages of the invention will be clarified with reference to theensuing detailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a schematic structure of aclassifying apparatus according to the present embodiment.

FIG. 2 is a perspective view illustrating a structure of an upper platein the classifying apparatus of FIG. 1.

FIG. 3 is a perspective view illustrating a structure of an intermediateplate having a hollow serving as a flow path through which an emulsionflows, and providing a plate-to-plate distance (smallest length) betweenthe upper plate and a lower plate, in the classifying apparatus of FIG.1.

FIG. 4 is a perspective view illustrating a structure of the lower platein the classifying apparatus of FIG. 1.

FIG. 5(a) is a front view illustrating how to measure a dynamic advanceangle, and FIG. 5(b) is a front view illustrating-how to measure adynamic retreat angle.

FIGS. 6(a) through 6(c) are cross-sectional views illustrating aclassification mechanism of an oil-in-water type emulsion which passesthrough the flow path.

FIG. 7 is a cross-sectional view illustrating a passage mechanism of anoil-in-water type emulsion which passes through the flow path.

FIG. 8 is a cross-sectional view illustrating a behavior of anoil-in-water type emulsion when it flows through a flow path made ofglass only.

FIG. 9 is a front view illustrating an exemplary apparatus connected tothe classifying apparatus.

FIG. 10 is a front view illustrating another exemplary apparatusconnected to the classifying apparatus.

FIG. 11 is a graph showing droplet diameter distributions of (a) liquiddroplets contained in an emulsion before being classified and (b) liquiddroplets contained in an emulsion after being classified in Example 5.

FIG. 12 is a diagram illustrating a microscope image showing a state ofan emulsion before being classified in Example 5.

FIG. 13 is a diagram illustrating a microscope image showing a state ofan emulsion after being classified in Example 5.

FIG. 14 is a graph showing droplet diameter distributions of (a) liquiddroplets contained in an emulsion before being classified and (b) liquiddroplets contained in an emulsion after being classified in ComparativeExamples 2 and 3.

FIG. 15 is a graph showing droplet diameter distributions of (a) liquiddroplets contained in an emulsion before being classified and (b) liquiddroplets contained in an emulsion after being classified in Examples 10and 11.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will describe one embodiment of the present invention. Aclassifying apparatus according to the present embodiment has a flowpath having a desired depth or width smaller than the largest diameterin liquid droplets contained in the emulsion, the flow path having thedesired depth or width allowing the emulsion to pass therethrough,wherein at least a part of walls forming the flow path is made of amaterial having affinity with the liquid droplets contained in theemulsion.

More specifically, examples of the classifying apparatus according tothe present embodiment include an apparatus having a structure (flowpath) through which an emulsion flows, wherein the flow path is providedbetween at least two plates that are separated by a distance less thanthe largest diameter in liquid droplets contained in the emulsion.

The above arrangement allows an emulsion to pass through the flow path.This causes coalescence of liquid droplets larger than the smallestdepth or width of the flow path, thus causing a separation into (a)large liquid droplets grown in size by the coalescence and (b) tinyliquid droplets staying without coalescence. The large liquid dropletssufficiently coalesce with one another to form one continuous phase.Then, for demulsification of the emulsion, the emulsion is usuallyseparated into two phases and discharged. The two phases are (i) acontinuous phase derived from liquid droplets and (ii) a continuousphase derived from a dispersion medium of the emulsion. In addition, theabove arrangement enables a prompt classification (demulsification) ofan emulsion having micro-diameter liquid droplets dispersed therein,generated by an apparatus such as the “micromixer”, and an emulsioncontaining an emulsifier (surfactant). This will be described below.

First, the following will describe an emulsion to be classified by theclassifying apparatus according to the present embodiment.

An emulsion according to the present embodiment has (a) a liquid(dispersion medium) and (b) other type of liquid, wherein particles ofthe liquid (b) in the form of colloidal particles or particles largerthan colloidal particles are dispersed in the liquid (a). In thefollowing description, the particles of the liquid refer to liquiddroplets.

A liquid droplet contained in the emulsion to be classified(demulsified) by the classifying apparatus according to the presentembodiment has more preferably a diameter in a range from 1 μm to 100μm, further preferably a diameter in a range from 10μm to 50 μm.

Usually, the emulsion is a dispersed system of water and an organicphase, i.e. a system in which liquid droplets are dispersed in otherliquid that do not dissolve them. Specifically, examples of the emulsioninclude: an oil-in-water (O/W) type emulsion in which an organic phase(liquid droplets) is dispersed in water (dispersion medium); and anwater-in-oil (W/O) type emulsion in which water (liquid droplets) aredispersed in an organic phase (dispersion medium).

Examples of organic solvents making up the organic phase include:aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatichydrocarbons such as heptane, hexane, heptane, octane, nonane, decane,dodecane, and tridecane; alicyclic hydrocarbons such as cyclopentane andcyclohexane; halogenated hydrocarbons such as methylene chloride,chloroform, and chlorobenzene; ethers such as dimethyl ether, diethylether, ethylene glycol dimethyl ether, propylene glycol dibutyl ether,and tetrahydrofuran; alcohols having approximately 6 to 20 carbon atoms(alcohols may be composed of any types of hydrocarbon radicals such asstraight-chain, branched-chain, and cyclic hydrocarbon radicals) such ashexanol, heptanol, octanol, decanol, and dodecanol; methyl isobutylketone; and butyl acetate.

Among the exemplary organic solvents, aromatic hydrocarbons, aliphatichydrocarbons, alicyclic hydrocarbons, and alcohols are used favorablybecause they have a high distribution coefficient (oil phase/aqueousphase) with respect to a solute (organic compounds), and allows a soluteto be distributed in the oil phase in a high proportion. Therefore, whenaromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons,and alcohols are used for organic solvents, a classifying apparatusaccording to the present embodiment can easily demulsify an emulsiongenerated by extraction of a solute from an aqueous phase, and promptlyextract a solute into an oil phase.

Further, the foregoing emulsion may contain an emulsifier, such assurfactant and protective colloid, for stabilization of the emulsion.

Examples of surfactants include: anionic surfactants such asalkylsulfate sulfonate, alkylbenzenesulfonate, alkylsulfosuccinate,alkyl diphenyl ether disulfonate, polyoxyethylene alkali sulfate, andpolyoxyethylene alkyl phosphate; nonionic surfactants such aspolyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene alkylether, polyoxyethylene alkyl phenol ether, polyoxyethylene fatty acidester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acidester, polyoxyethylene alkylamine, and glycerine fatty acid ester;cationic surfactants such as alkylamine salts and quaternary ammoniumsalts including tetraalkyl ammonium halide and benzil trialkyl ammoniumhalide.

Examples of protective colloids include: polyvinyl alcohols such aspartially saponified polyvinyl alcohol, completely saponified polyvinylalcohol, sulfonate-modified polyvinyl alcohol, carboxyl-modifiedpolyvinyl alcohol, silanol-modified polyvinyl alcohol; and cellulosederivatives such as hydroxyethyl cellulose, methyl cellulose, andcarboxymethyl cellulose.

Further, the emulsifier may be a combination of different types ofemulsifiers, such as surfactant and protective colloid.

For example, an emulsion is generated by washing an organic phaseobtained by an organic synthesis reaction, when a surfactant(specifically, e.g. tetraalkylammonium salt and benzyltrialkylammoniumsalt) is used as a phase-transfer catalyst, or when a substrate and areaction product in the organic synthesis reaction are ammonium salt andcarboxylate salt. Liquid droplets contained in this emulsion have adiameter of about 10 μm to 50 μm. Therefore, it is possible to realize amore favorable classification (demulsification) of the emulsion with theuse of the classifying apparatus according to the present embodiment.

FIG. 1 is a perspective view illustrating a schematic structure of aclassifying apparatus 1 according to the present embodiment. Asillustrated in FIG. 1, the classifying apparatus 1 has a structure inwhich an intermediate plate 3 (see FIG. 3) having a hollow that servesas a flow path through which an emulsion flows, is sandwiched between anupper plate (plate member) 2 (see FIG. 2) and a lower plate (platemember) 4 (see FIG. 4). That is, as illustrated in FIG. 3, the hollowformed between the upper plate 2 and the lower plate 4, both of whichare separated by the intermediate plate 3, is the flow path throughwhich the emulsion passes. As illustrated in FIGS. 1 and 2, the upperplate 2 is provided with a supply port 5 that supplies an emulsion andan exit 6 that discharges a classified (demulsified) liquid.

The smallest length (plate-to-plate distance) between the upper plate 2and the lower plate 4 in the classifying apparatus 1 according to thepresent embodiment, i.e. thickness of the intermediate plate 3 is set tobe equal to or less than the largest diameter in liquid dropletscontained in the emulsion to be passed, and to be equal to or less thana desired classification length, i.e. a desired diameter of liquiddroplets contained in the emulsion to be classified. Preferably, it isset to be equal to or less than a volume average diameter of the liquiddroplets. For example, in a case where an oil-in-water type emulsion inwhich liquid droplets that are oil droplets whose maximum diameter is 10μm are dispersed in an aqueous phase, is separated into, as a continuousphase, an oil phase realized by coalescence of liquid droplets havingmore than 10 μm in diameter, the smallest length, i.e. thickness of theintermediate plate 3 is set to be equal to or less than 10 μm.

Specifically, the smallest length, which differs depending upon the typeof emulsion to be classified (demulsified), is preferably in a rangefrom 1 to 100 μm. With the smallest length in this range, a residencetime required for liquid-separation tends to be shortened. Especially,in a case when an emulsion having tiny liquid droplets that allow aquick extraction thereof, like an emulsion generated by a micromixer, isused, the smallest length is preferably in a range from 1 to 50 μm. Notethat, the “flow path” herein refers to a region having a depth or widthsmaller than the largest diameter in liquid droplets contained in theemulsion to be flown, in an area of the classifying apparatus 1 wherethe emulsion flows. The use of a classifying apparatus of the presentembodiment enables a favorable classification into liquid dropletshaving a liquid droplet diameter (volume average diameter of liquiddroplets) in a range of about 1 to 100 μm, more preferably in a range ofabout 10 to 50 μm.

That is, a thickness of the intermediate plate 3, i.e. the smallestwidth or depth (smallest length) of the flow path is set to be smallerthan the largest diameter of liquid droplets contained in an emulsion tobe classified, and to be a length that the operator desires in the abovelength range. In other words, at a desired length, set by the operator,within a range that meets the above conditions, most of the liquiddroplets having a diameter larger than the set length coalesce with oneanother to form a continuous phase when passing through the flow path.

In the classifying apparatus 1 according to the present embodiment, aspacing between the upper plate 2 and the lower plate 4 is a flow paththrough which an emulsion flows. In the cross section of the flow path,a length of a side of the plate where it comes into contact with anemulsion in a direction perpendicular to a flow direction (length of theupper plate 2 or the lower plate 4 in its extended direction in thecross section of the flow path) is preferably 10 or more times as largeas the smallest length between the upper plate 2 and the lower plate 4,further preferably 100 or more times as large as the smallest lengthbetween the upper plate 2 and the lower plate 4. In other words, whenthe shape of cross section of the flow path is rectangular, and thedepth of the flow path is the smallest length, a direction orthogonal tothe depth, i.e. a width (breadth) is more preferably 10 or more times aslarge as the depth, further preferably 100 or more times. For example,referring to FIG. 3, when arrows represent flow directions of theemulsion, a length (distance) of a breadth (in the lateral direction) ina plane perpendicular to the flow direction is more preferably 10 ormore times as large as a length (distance) k of the depth (in theperpendicular direction) d, further preferably 100 or more times.

It is preferable that a side of the plate where it comes into contactwith an emulsion preferably has a length (breadth) of ten times or moreas large as the smallest length, which tends to bring an excellentclassification (demulsification) effect. That is, with the arrangementin which in the cross section of the flow path, the largest width is tentimes or more as large as the smallest width in the cross section,liquid droplets contained in the emulsion can deform in the flow path tofit in the smallest width and can spread in a direction of the largestwidth. This arrangement allows for an easier supply of the emulsion,which realizes to reduce a pressure drop that occurs when the emulsionis supplied to the classifying apparatus 1.

Specifically, as illustrated in FIG. 1, examples of a method forseparating the upper plate 2 and the lower plate 4 from each other, i.e.a method for forming the flow path includes: (a) a method of sandwichingthe intermediate plate 3 having the hollow that is a flow path of theemulsion between the upper plate 2 and the lower plate 4; (b) a methodof forming the hollow (flow path) by grinding an inner surface of atleast one of two plates (upper plate 2 and lower plate 4); and (c) amethod of coating at least one of the two plates with a resist material,etching a portion of the resist material corresponding to the flow path,hardening this resist material, and bonding the two plates so that theflow path is formed therebetween.

In the classifying apparatus 1 of the present invention, a length of theflow path through which the emulsion flows is not particularly limitedas far as the length is the one that provides a sufficient residencetime to classify (demulsify) the emulsion, except for restrictions onstructure of the apparatus, e.g. structural conditions for a sufficientprovision of the smallest length.

The length of the flow path (flow path length) is more preferably alength capable of existing in the flow path at least two dropletscontained in the emulsion, further preferably more than the lengthcapable of existing in the flow path at least two droplets contained inthe emulsion. The above flow path length realizes more reliablecoalescence of liquid droplets contained in the emulsion inside the flowpath. Note that, a coalescence mechanism of two liquid droplets will bedescribed later.

Specifically, the flow path length is more preferably in a range from 1mm to 10 cm, further preferably in a range from 2 mm to 5 cm. The flowpath length shorter than 1 mm could cause a difficulty in preparation ofthe classifying apparatus and an insufficient classification of liquiddroplets contained in the emulsion. On the other hand, the flow pathlength longer than 10 cm could increase a pressure drop that occurs whenthe emulsion is flown through the flow path, resulting in inefficiency.

Referring to FIG. 3, the following will describe the flow path length ofthe flow path through which the emulsion flows. The flow path length ofthe flow path corresponds to a distance in an emulsion flow direction(length “1” in FIG. 3) in an area of the intermediate plate 3 where thehollow is formed. Note that, in FIG. 3, the shortest flow path length ofthe flow path corresponds to a distance from the supply port 5 to theexit 6, both of which are provided to the upper plate 2.

In the classifying apparatus 1 of the present embodiment, at least apart of the flow path is made of a material having more affinity withliquid droplets contained in the emulsion (droplet affinity material).

The affinity with liquid droplets is a property capable of wetting theliquid droplets contained in the emulsion. On the other hand,non-affinity with liquid droplets is a property of repelling: the liquiddroplets contained in the emulsion. For example, when the foregoingemulsion is an oil-in-water (O/W) type emulsion, the droplet affinitymaterial exhibits lipophilicity, whereas the droplet non-affinitymaterial exhibits hydrophilicity. On the other hand, when the foregoingemulsion is a water-in-oil (W/O) type emulsion, the droplet affinitymaterial exhibits hydrophilicity, whereas the droplet non-affinitymaterial exhibits lipophilicity.

Specifically, in the classifying apparatus 1 according to the presentembodiment, surfaces of plates (upper plate 2 and lower plate 4) can behydrophilic or lipophilic (hydrophobic), but at least a part of wallsforming the flow path is made of droplet affinity material.Specifically, in order to classify an oil-in-water type emulsion, i.e.in order to flow the oil-in-water type emulsion through the flow path ofthe classifying apparatus 1, at least one of the upper plate 2 and thelower plate 4 which come into contact with the emulsion preferably has alipophilic surface. On the other hand, in order to classify awater-in-oil type emulsion, in order to flow the water-in-oil typeemulsion through the flow path of the classifying apparatus 1, at leastone of the upper plate 2 and the lower plate 4 which come into contactwith the emulsion preferably has a hydrophilic surface.

Here, hydrophilicity is a property of having an affinity for water.Material having hydrophilicity (hydrophilic material) represents amaterial having a dynamic contact angle of water in oil of less than 90degree. A surface free energy of the hydrophilic material is morepreferably 70 mN/m (70 dyne/cm) or more, which tends to exhibit anaffinity for water.

Specifically, examples of the hydrophilic material include glass,cellulose, ion exchange resin, poval, and metal. Especially, glass andmetal are favorable for the hydrophilic material.

Meanwhile, lipophilicity (hydrophobicity) is a property of having anaffinity for organic solvent. Material having lipophilicity (lipophilicmaterial) represents a material having a dynamic contact angle of waterin oil of 90 degree or more. More specifically, it is more preferablethat the lipophilic material is a material having a surface free energyof 65mN/m (65 dyne/cm) or less. Such a lipophilic material tends to havean affinity for organic solvent. It is further preferable that thelipophilic material is a material having a surface free energy in arange from 1 to 50 mN/m (1 to 50 dyne/cm).

Specifically, examples of the lipophilic material include: fluorineresin such as polytetrafluoroethylene, ethylene-tetrafluoroethylenecopolymer, and polyvinylidene fluoride; olefin resin such aspolyethylene, polypropylene, ethylene-propylene copolymer, polystyrene,and polyvinyl chloride; and polydimethylsiloxane. Especially, fluorineresin having an excellent chemical resistance is favorable for thelipophilic material.

Referring to FIGS. 5(a) and 5(B), the following will describe thedynamic contact angle of water in oil. Note that, “oil” of “water inoil” is the same as a material making up the liquid droplets of theforegoing emulsion (organic solvent).

The dynamic contact angle is measured by means of a contact angle meter.Then, “oil” is used as an organic solvent (organic phase) contained inthe emulsion. A static contact angle, a dynamic advance angle, and adynamic retreat angle of water in the oil (e.g. dodecane or octanol) onthe hydrophilic material or lipophilic material (glass or fluorineresin) are measured. More specifically, as illustrated in FIG. 5(a),measurement of the dynamic contact angle is performed as follows: Acontact angle (dynamic advance angle) of liquid droplets (water) wettedand spread when they are forced to drop from a needlepoint is measured.Further, as illustrated in FIG. 5(b), a contact angle (dynamic retreatangle) of the liquid droplet drawn up from the needlepoint is measured.It should be noted that the dynamic contact angle of less than 90 degreemeans that the dynamic advance angle and the dynamic retreat angle areless than 90 degree each. The dynamic contact angle of 90 degree or moremeans that the dynamic advance angle and the dynamic retreat angle are90 degree or more each.

Next, the following will describe a coalescence mechanism of liquiddroplets when the emulsion is classified by means of a classifyingapparatus according to the present embodiment. The following descriptionwill be given, as a concrete example, based on a case where the emulsionhaving oil droplets dispersed in water (dispersion medium) passesthrough a flow path made of glass and fluorine resin. Note that, glassis a hydrophilic material having a dynamic contact angle of water in oilof less than 90 degree. Further, fluorine resin is a lipophilic materialhaving a dynamic contact angle of water in oil of 90 degree or more.

Condition (i): flow path depth (smallest length)<diameter of an oildroplet (liquid droplet) contained in the emulsion

FIGS. 6(a) through 6(c) are cross sectional views illustrating aclassification mechanism of an oil-in-water type emulsion passingthrough the flow path. As illustrated in FIG. 6(a), when an oil droplet(hereinafter referred to as liquid droplet) contained in the emulsionhas a diameter larger than the smallest length (flow path depth) in thecross section of the flow path of the classifying apparatus 1, theliquid droplet deforms as it enters the flow path (microchannel). Thisincreases a surface area of the liquid droplet and causes an unstableinterface of the liquid droplet. More specifically, an affinity betweenthe liquid droplet and material forming the flow path causes the liquiddroplet to be wetted on the surface of fluorine resin. On the otherhand, since water contained in the emulsion has a high affinity forglass (having a dynamic contact angle of 0 degree with respect toglass),.water is wetted and spread on the surface of glass all the time.

That is, as illustrated in FIG. 6(a), water is repelled on the fluorineresin (PTFE) having a 90-degree or more dynamic advance angle (θ2 inFIG. 6(a)) and a 90-degree or more dynamic retreat angle (θ4 in FIG.6(a)) of water in oil. This causes a slip along a flow of the water. Onthe other hand, the liquid droplet is wetted and spread on the fluorineresin, but is repelled on the glass surface (θ1 and θ3 in FIG. 6(a)).This difference in wettability between the water and the liquid dropleton the fluorine resin causes difference of a speed in the flow pathbetween the water and the liquid droplet. More specifically, in the flowpath, the water passes through the flow path faster than the liquiddroplet.

Next, as illustrated in FIG. 6(b), as a small liquid droplet (whosediameter is larger than the depth of the flow path) that is smaller thanthe liquid droplet staying in the flow path enter the flow path, thesmall liquid droplet deforms in the flow path in a similar manner as theabove liquid droplet. The shape of the small liquid droplet at thismoment is the same as the large liquid droplet. Then, the large liquiddroplet and the small liquid droplet flow through the flow path. Inflowing through the flow path, the small liquid droplet undergoes asmaller force opposite in direction to the flow of the water from wallsurfaces than the large liquid droplet. Therefore, the small liquiddroplet relatively has a high speed in the flow path than the largeliquid droplet. Thus, the small liquid droplet catches up with the largeliquid droplet. This will be described below in detail.

For example, an emulsion immediately after being generated by amicromixer has a diameter distribution of liquid droplets. When theemulsion enter the flow path, a force F acting on a liquid dropletcontained in the emulsion is expressed by the following equation (1):F=F1+F2+F3   (1)

where F1 is a force to which the liquid drop is subjected by a flow ofwater (water flow), F2 is a force to which the liquid droplet issubjected by the surface of fluorine resin in the opposite direction tothe flow of water, and F3 is a force to which the liquid droplet issubjected by the surface of glass in the opposite direction to the flowof water.

Here, a volume of arbitrary large liquid droplet is set to VL, and thatof a small liquid droplet is set to VS in the emulsion. Forces to whichthe large liquid droplet and small liquid droplet are subjected by thewall surfaces are expressed by the following equation (2):F2=−K2A2; F3=−K3A3   (2)

Here, A2 is a contact area between a liquid droplet and the fluorineresin, A3 is a contact area between a liquid droplet and the surface ofglass, and K2 and K3 are proportionality constants.

Further, constant areas between a liquid droplet and the wall surfacesare expressed by the following equations (3):A2∝V; A3∝V   (3).

When F2,L is a force to which the large liquid droplet is subjected bythe surface of fluorine resin, F3,L is a force to which the large liquiddroplet is subjected by the surface of glass, F2,S is a force to whichthe small liquid droplet (small droplet) is subjected by the surface offluorine resin, and F3,S is a force to which the small liquid droplet issubjected by the surface of glass, the following equations (4) areformulated:(F2,L)/(F2,S)=VL/VS;(F3,L)/(F3,S)=VL/VS   (4).

The force F1 to which the liquid droplet is subjected by the flow ofwater is proportional to a relative velocity with respect to water and aprojected area S of the liquid droplet in the flow direction. Here, theprojected area S is expressed by the following equation (5):S∝V^(0.5)   (5).

Here, when F1,L is a force to which the large liquid droplet issubjected by the flow of water, and F1,S is a force to which the smallliquid droplet is subjected by the flow of water, the following equation(6) is formulated:(F1,L)/(F1,S)=(VL/VS)^(0.5)   (6).

When a force acting on the large liquid droplet is compared with a forceacting on the small liquid droplet, from the equations (1), (4), and (6)the following equation (7) is obtained:(FL/FS)<(VL/VS)   (7).

Here, an equation of motion of liquid droplets is expressed by thefollowing equations (8) and (9):F=m·a   (8); and(mL/mS)=(VL/VS)   (9)

where mL is a mass of the large liquid droplet, and mS is a mass of thesmall liquid droplet.

Now, when aL is an acceleration acting on the large liquid droplet, andaS is an acceleration acting on the small liquid droplet, the followingequation (10) is obtained:aL<aS   (10).

Here, both aL and aS are accelerations acting in the opposite directionto the flow of water and are negative values.

A velocity of the liquid droplets immediately after entering the flowpath is equal to a water flow velocity (v0) regardless of a size of theliquid droplets. When t is a time elapsed since the liquid dropletsenter the flow path, vL is a velocity of the large liquid droplet in theflow path, and vS is a velocity of the small liquid droplet in the flowpath, vL and vS are expressed respectively by the following equations(11) and (12):vL=v0+aL×t   (11); andvS=v0 30 aS×t   (12).

From the equations (8) through (12), vL>vS is obtained. That is, whenthe liquid droplets enter the flow path, there occurs a difference invelocity between the large liquid droplet and the liquid small dropletdue to difference in magnitude of forces to which the liquid droplets issubjected by the wall surfaces. In this manner, as illustrated in FIG.6(b), the small liquid droplet catches up with the large liquid droplet.

As illustrated in FIG. 6(c), when the small liquid droplet catches upwith the large liquid droplet, the two droplets are wetted and spread onthe surface of fluorine resin and coalesce with each other into oneliquid droplet.

Condition (ii): flow path depth (smallest length) >diameter of a liquiddroplet contained in the emulsion

As illustrated in FIG. 7, the liquid droplets are discharged out of theexit of the flow path at the same velocity as water, without beingaffected by the wall surfaces of the classifying apparatus 1. In otherwords, when a diameter of a liquid droplet contained in the emulsion issmaller than a flow path depth, the droplet passes without being wettedon the fluorine resin, that is, the droplet is discharged at the samevelocity as water because it is not affected by a material forming theflow path. Therefore, in this case, there occurs no droplet coalescenceresulting from an influence of the wall surfaces of the flow path.However, there may occur droplet coalescence due to collision betweendroplets by inertia.

Further, for example, as illustrated in FIG. 8, when an oil-in-watertype emulsion is flown through a flow path made of glass only, thereoccurs no droplet coalescence resulting from an influence of the wallsurfaces of the flow path, since the liquid droplets are not wetted onthe surface of glass regardless of diameters of the liquid dropletscontained in the emulsion. Further, for example, even when two liquiddroplets come into contact with each other in the flow path, both ofthem resist coalescing with each other since there are not wetted on thewall surfaces.

As described above, for coalescence of liquid droplets in the flow path,the following conditions are necessary: (i) a liquid droplet has adiameter larger than a depth of the flow path; and (ii) liquid dropletsare wetted on at least a part of material forming the flow path.

It should be noted that the above description has given based on acoalescence mechanism of liquid droplets contained in an oil-in-watertype emulsion. Also, in a water-in-oil type emulsion, liquid dropletscontained in the emulsion coalesce with each other in a similar manneras described above.

Now, the following will describe a classifying method according to thepresent embodiment.

To classify (demulsify) an emulsion, the emulsion is supplied from thesupply port 5 of the classifying apparatus 1 so that it can be passedthrough the flow path. In other words, the emulsion is supplied from thesupply port 5, flown through the flow path, classified (demulsified) inthe flow path, and discharged out of the exit 6.

A residence time of the emulsion in the flow path is set to be a timesufficient for classification (demulsification) of liquid dropletscontained in the emulsion. It is more preferable that the residence timeis set to be in a range from 0.001 to 10 seconds.

The residence time of the emulsion is preferably not less than 0.001seconds, which tends to bring an easier manufacture of the apparatus.Also, the residence time of the emulsion is preferably not more than 10seconds, which tends to reduce a size of the apparatus. The emulsionresidence time of less than 0.001 seconds may cause such an insufficientphase-separation of the emulsion that liquid droplets contained in theemulsion are discharged before coalescing with one another.

A flow rate of an emulsion flowing through the flow path (emulsionsupply rate) in the classifying apparatus 1 of the present embodimentdiffers depending upon types of emulsion. Usually, for an emulsionsuperior in phase-separation, like a water/dodecane emulsion, whichexhibits a phase-separation rate of not less than 1 m/min in stationaryphase-separation, a flow rate of the emulsion flowing through the flowpath is not less than 1 m/min, preferably about 2 to 10 m/min. Such aflow rate enables a sufficient classification. For an emulsion inferiorin phase-separation which exhibits a phase-separation rate of less than1 m/min in stationary phase-separation, a failure of classification mayoccur if a flow rate of the emulsion flowing through the flow path isnot less than 1 m/min even with the use of a classifying apparatus ofthe present invention. For example, for a stable emulsion that is notseparated in a day, like a water/dodecane emulsion containing asurfactant, liquid droplets in the emulsion can coalesce with oneanother for classification under a condition that a flow rate of theemulsion flowing through the flow path is adjusted to be in a range ofabout 0.01 m/s to 1 m/s.

That is, the emulsion is supplied to the flow path in such a manner thatthe emulsion stays in the flow path for the residence time in the aboverange.

As described above, a classifying apparatus according to the presentembodiment is a classifying apparatus which has a flow path having adesired depth or width smaller than the largest diameter in liquiddroplets contained in the emulsion, wherein at least a part of wallsforming the flow path is made of a material having affinity with theliquid droplets.

With this arrangement, liquid droplets larger in size than a desireddepth or width that is smaller than the largest diameter of liquiddroplets in the flow path, deform in passing through the flow path,which causes an unstable liquid-liquid interface. Then, when unstableliquid droplets come into contact with each other in a part (state)where the liquid droplets are wetted on the droplet affinity material,they coalesce with each other to be in a stable state.

That is, in passing through the flow path, a liquid droplet larger thanthe desired depth or width is more likely to coalesce with other liquiddroplet. On the other hand, a liquid droplet smaller than the desireddepth or width passes through the flow path without undergoing a forcefrom the wall surfaces of the flow path. Therefore, the liquid dropletsmaller than the desired depth or width hardly coalesces with otherliquid droplet in the flow path.

With this arrangement, under a condition where the smallest length ofthe flow path is set to be a desired value, a liquid droplet smallerthan the smallest distance is directly discharged out of the flow path,without coalescing. On the other hand, a liquid droplet larger than thesmallest length coalesces with other liquid droplet to form a largerliquid droplet, and the larger liquid droplet is then discharged. Afterdischarged, the larger liquid droplet coalesces with other larger liquiddroplet to form one phase (continuous phase). Further, a liquid dropletsmaller than the smallest length keeps in a small liquid droplet stateeven after having been discharged out of the flow path. Therefore, withthe above arrangement, liquid droplets contained in the emulsion areclassified so that only liquid droplets having a size smaller than adesired size can be obtained.

Further, at least a part of walls forming the flow path is preferablymade of a droplet non-affinity material, which can realize to reduce apressure drop that occurs during supply of the emulsion.

Especially, it is preferable that two walls forming the flow path arerealized by two plate members separated from each other at a distancesmaller than the largest diameter of liquid droplets contained in theemulsion, and that the plate members are respectively made of two sheetsof plate materials, droplet affinity material and droplet non-affinitymaterial.

Here, when liquid particles (liquid droplets) in the emulsion are waterdroplets, the droplet affinity material is a hydrophilic material, andthe droplet non-affinity material is a lipophilic material. On the otherhand, when liquid droplets in the emulsion are oil droplets, the dropletaffinity material is a lipophilic material, and the droplet non-affinitymaterial is a hydrophilic material.

It should be noted that the arrangement of the classifying apparatus 1in which the flow path is formed by three plates: the upper plate 2, theintermediate plate 3 having a hollow; and the lower plate 4, allows theflow path to have an arbitrary depth (width) only with a thicknesschange of the intermediate plate 3. Therefore, as compared with aconventional classifying apparatus, the classifying apparatus 1 ismanufactured at very low cost with an easy maintenance and nomicrofabriaction requirement.

Further, in the classifying apparatus 1 according to the presentembodiment, the emulsion reliably passes through the flow path that isset to have a desired width or depth in its cross section. With thisarrangement, a diameter of a liquid droplet discharged out of the flowpath can be adjusted to be not more than a given diameter. In addition,as compared with a conventional arrangement, the arrangement of theclassifying apparatus 1 can obtain liquid droplets having a narrowerdroplet diameter distribution range. In other words, as compared withthe conventional arrangement, the arrangement of the classifyingapparatus 1 can obtain liquid droplets having more uniform diameters.

Further, the classifying apparatus 1 according to the present embodimentchanges, into unstable shapes, liquid droplets contained in the emulsionpassing through the flow path, which facilitates the liquid droplets tocoalesce with each other. That is, when two liquid droplets that existin the flow path come into contact with each other at portions wherethey are wetted on the droplet affinity material, they coalesce witheach other to be more stable (with a spontaneously acting force thatdecreases their surface areas). Therefore, as compared with theconventional arrangement, the arrangement of the classifying apparatus1, even in a condition where a flow rate (supplied amount) of theemulsion supplied to the classifying apparatus 1 is changed to somedegree, can perform a favorable classification as far as the flow rateis a flow rate at which liquid droplets (liquid droplets having unstableshapes) can come into contact with each other in the flow path.

Note that, plates (upper plate 2 and lower plate 4) used in theclassifying apparatus 1 of the present embodiment have at leasthydrophilic and/or hydrophobic surfaces. Specifically, examples of theplates include plates made of hydrophilic material, plates made ofhydrophobic material, and plates coated with hydrophilic material and/orhydrophobic material on their surfaces that comes into contact with anemulsion made of a given material. That is, the plates used in theclassifying apparatus 1 of the present embodiment exhibit hydrophilicityor lipophilicity only on their surfaces that comes into contact with theemulsion. For example, the plates may be obtained by the followingprocess: a glass substrate or the like is subjected to fluorine-resinprocessing or the like to obtain a glass substrate having lipophilicityon its surface.

The above plates are separated from each other at least one part thereofat a distance smaller than the largest diameter of liquid dropletscontained in the emulsion. For example, the plates may be bent on onepart thereof. Note that in this case, the “flow path” is an area thathas a width smaller than the largest diameter of liquid droplets.

The supply port 5 of the classifying apparatus 1 of the presentinvention may be connected to a micromixer which can generate anemulsion having tiny liquid droplets. That is, as illustrated in FIG. 9,the supply port 5 of the classifying apparatus 1 of the presentinvention may be arranged so as to directly supply the emulsiongenerated by the micromixer to the flow path. Here, the micromixer is anapparatus which can produce submicron liquid droplets. Examples of themicromixer include a micromixer described in “Utilization of Micromixerfor Extraction Processes” (Kurt Benz and seven others, Chem. Eng.Technol. 24, 1, 2001, p 11-17). Note that, in the above arrangement, atotal amount of aqueous phase (water) and oil phase (organic solvent)supplied to the micromixer determines an amount (rate) of emulsionsupplied to the classifying apparatus 1.

Alternatively, for example, as illustrated in FIG. 10, the emulsiongenerated by the micromixer may be supplied to the classifying apparatus1 through another supply apparatus (microsyringe) or the like. Notethat, in this arrangement, the amount (rate) of emulsion supplied to theclassifying apparatus 1 can be arbitrarily determined regardless of theamount of aqueous phase and oil phase supplied to the micromixer.

Further, in order to continuously and promptly separate a solutiondischarged out of the exit 6 of the classifying apparatus 1, aliquid-separating apparatus, termed as a settler, may be connected tothe exit 6 of the classifying apparatus 1.

As to positions of the supply port 5 and the exit 6, in addition to thepositions illustrated in FIGS. 1 and 2, the supply port 5 and the exit 6may be positioned in a upward direction, downward direction, and lateraldirection. Specifically, for example, when the classifying apparatus 1is composed of three plates: the upper plate 2; the intermediate plate3; and the lower plate 4, the supply port 5 and/or the exit 6 may beattached to the upper plate 2, the intermediate plate 3, and the lowerplate 4.

The number of the supply ports 5 and the exits 5 may be one each.Alternatively, the number of the supply ports 5 and the exits 6 may bemore than one each.

In FIG. 2, the flow path (hollow) is rectangular in shape. However, theshape of the flow path through which the emulsion passes may be, forexample, a shape having a narrower part on the side where the supplyport 5 is provided and a wider part on the side where the exit 6 isprovided, and vice versa.

In FIG. 1, the classifying apparatus 1 has one flow path. The number offlow paths may be more than one.

Specifically, examples of the classifying apparatus 1 include: (i) theapparatus as illustrated in FIG. 1; (ii) an apparatus having a pluralityof the apparatus of FIG. 1 arranged in all directions, wherein onecommon supply port 5 and a plurality of exits 6 are provided; (iii) anapparatus having disk-shaped plates (upper plate 2, intermediate plate3, and lower plate 4), wherein an emulsion is supplied from a center ofthe disk-shaped plate and discharged from its circumferential part; and(iv) an apparatus having an alternately and repeatedly laminatedstructure with the upper plate 2, the lower plate 4, and theintermediate plate 3 having a flow path.

Further, in the above description, the flow path of the classifyingapparatus 1 is realized by plates (upper plate 2, intermediate plate 3,and lower plate 4). Alternatively, the flow path may be realized by atube, for example.

With the use of the classifying apparatus 1 according to the presentembodiment, even a stable emulsion containing a surfactant (emulsifier),for example, can be classified.

A classifying apparatus according to the present embodiment may have astructure in which an emulsion is flown between at least two platesseparated from each other at a distance smaller than the largestdiameter of liquid droplets contained in the emulsion.

Further, a classifying apparatus according to the present embodiment maybe such that the smallest length between the plates is 1 μm to 100 μm.

Still further, a classifying apparatus according to the presentembodiment may be such that in a cross section of an emulsion-flowingstructure, a side of the plate where it comes into contact with anemulsion in a direction perpendicular to a flow direction has a lengthof ten times or more as large as a plate-to-plate distance (smallestlength).

Yet further, a classifying apparatus according to the present embodimentmay be such that at least one of the plates that comes into contact withan emulsion has a hydrophobic surface.

Further, a classifying apparatus according to the present embodiment maybe arranged such that the hydrophobic surface is made of fluorine resinor polyolefine resin.

Still further, a classifying apparatus according to the presentembodiment may be arranged such that the emulsion is the one obtained bymixing emulsion materials in a micromixer.

Yet further, a classifying apparatus according to the present embodimentmay be arranged such that a settler is connected to the exit.

Further, a classifying apparatus according to the present embodiment maybe arranged so as to be a classifying apparatus for classifying anoil-in-water type emulsion, including a flow path having a spacingsmaller than the largest diameter in liquid droplets contained in theoil-in-water type emulsion, wherein at least a part of walls forming theflow path is made of a material having a dynamic advance angle and adynamic retreat angle of water in oil of 90 degree or more each.

Still further, a classifying apparatus according to the presentembodiment may be arranged so as to be a classifying apparatus forclassifying a water-in-oil type emulsion, including a flow path having aspacing smaller than the largest diameter in liquid droplets containedin the water-in-oil type emulsion, wherein at least a part of wallsforming the flow path is made of a material having a dynamic advanceangle and a dynamic retreat angle of water in oil of less than 90 degreeeach.

Further, with the use of a classifying apparatus according to thepresent embodiment, for example, even an emulsion generated byextraction of a solute of an organic compound to an aqueous phase can bedemulsified promptly. Thus, the classifying apparatus according to thepresent embodiment can favorably perform operations such as washing ofsolutes unstable toward water and extraction of effluents from aqueousphases.

Yet further, with the use of a classifying apparatus according to thepresent embodiment, it is possible to produce an emulsion composed ofonly liquid droplets having a submicroscopic diameter, for example.Then, the emulsion composed of only liquid droplets having asubmicroscopic diameter, which has been produced by using thisclassifying apparatus, is used favorably to manufacture products whichare absorbed into the body more quickly as their liquid droplets have asmaller diameter, in the industries such as food industry, agriculturalchemical industry, and pharmaceutical industry.

EXAMPLES

The following will describe the present invention in detail withreference to Examples and Comparative Example. However, the presentinvention is not limited to them.

(Diameter of Liquid Droplets Contained in an Emulsion)

A diameter of liquid droplets contained in a just-produced emulsion wasmeasured by means of a laser diffraction/scattering particle sizedistribution analyzer (HORIBA LA-920).

Specifically, after liquid droplets contained in the just-producedemulsion were stabilized in 0.5 wt % of sodium dodecyl sulfate aqueoussolution, diameters of the liquid droplets were measured.

It should be noted that an observation result obtained by observingliquid droplets contained in the just-produced emulsion by means of adigital microscope (VH-8000; produced by Keyence Corporation) was aboutthe same as a measurement result obtained by the measurement by means ofthe laser diffraction/scattering particle size distribution analyzer(HORIBA LA-920).

(Classifying Apparatus)

The following will describe a classifying apparatus used in Examples 1through 4 given below.

For the classifying apparatus, as illustrated in FIG. 1, used was aclassifying apparatus including: the upper plate 2 being provided withthe supply port 5 and the exit 6 for an emulsion; the intermediate plate3 having a hollow; and the lower plate 4, wherein the intermediate plate3 is sandwiched between the upper plate 2 and the lower plate 4.

Specifically, the intermediate plate 3 is provided with a hollow, as anemulsion flow path, having: (a) a flow path through which an emulsionflows, the flow path having a length of 5 cm (emulsion flow length of 5cm; indicated with “1” in FIG. 3); and (b) a breadth (length in adirection orthogonal to the smallest length in a cross section of theemulsion flow path; indicated with “k” in FIG. 3) of 1 cm. Morespecifically, in order to make a distance between the upper plate 2 andthe lower plate 4 (smallest length) have a desired value, used was theintermediate plate 3 made of aluminum foil and having a thickness (d) of12 μm, that is the same as the desired value (produced by Sun AluminiumInd., Ltd.) (See FIG. 2).

Then, the classifying apparatus 1 was made up by laminating the upperplate 2 (see FIG. 2), the intermediate plate providing the emulsion flowpath (see FIG. 3), and the lower plate 4 (see FIG. 4) in order, and thensandwiching the intermediate plate between the upper plate 2 and thelower plate 4 by sealing their side surfaces (see FIG. 1).

It should be noted that plates used as the upper plate 2 and the lowerplate 4 are as follows (surface treatment is not especially performed onthem):

Glass: glass for Präparat (2 mm in thickness; quartz glass; produced byEikoh Co., Ltd.)

PE: polyethylene sheet (6 mm in thickness; product name: SUNFRIC(general abrasion resistance grade: UE550); produced by Kyodo Co., Ltd.)

PP: polypropylene sheet (6 mm in thickness; product name: Kobe PolysheetPP; produced by Shin-Kobe. Electric Machinery Co., Ltd.)

PTFE: polytetrafluoroethylene sheet (2 mm in thickness; product name:PTFE sheet; Yodogawa Hu-Tech Co., Ltd.)

Example 1

For production of an emulsion, water and dodecane were supplied to amicromixer (produced by IMM GmbH; single mixer) at rates of 2.7 ml/minand 0.3 ml/min, respectively. Then, diameters of liquid dropletscontained in a just-produced emulsion were measured by means of thelaser diffraction/scattering particle size distribution analyzer (HORIBALA-920).

Next, an outlet of the micromixer was connected to the supply port 5 ofthe classifying apparatus including the upper plate 2 made of glass andthe lower plate 4 made of PE, and the emulsion was supplied to theclassifying apparatus at a rate of 3 ml/min. Then, liquids dischargedout of the exit 6 of the classifying apparatus were stored in ameasuring cylinder (7 mm in diameter). Of generated aqueous phase partand oil phase part, the aqueous phase part was observed. If the aqueousphase part was clouded, failure of demulsification of the emulsion isindicated with x. On the other hand, if the aqueous phase part wasclear, no-failure of demulsification of the emulsion is indicated withO. Observation results are shown in Table 1.

Example 2

Except for the use of a classifying apparatus including the upper plate2 made of glass and the lower plate 4 made of PP, obtained liquids wereobserved as in Example 1. Observation results are shown in Table 1.

Example 3

Except for the use of a classifying apparatus including the upper plate2 made of glass and the lower plate 4 made of PTFE, obtained liquidswere observed as in Example 1. Observation results are shown in Table 1.

Example 4

Except for the use of a classifying apparatus including the upper plate2 made of PTFE and the lower plate 4 made of PTFE, obtained liquids wereobserved as in Example 1. Observation results are shown in Table 1.TABLE 1 Example1 Example2 Example3 Example4 Upper Plate Glass GlassGlass PTFE Lower Plate PE PP PTFE PTFE Plate-to-Plate 12 12 12 12Distance (μm) Residence Time (s) 0.12 0.12 0.12 0.12 Flow Rate (m/s)0.42 0.42 0.42 0.42 Classification ◯ ◯ ◯ ◯

Comparative Example 1

The emulsion (5 ml) used in Example 1 was let stand in a measuringcylinder (7 mm in diameter) for one hour. After that, the emulsion wasobserved. As a result of the observation, there existed a whitish phaseon an interface between the aqueous phase part and the oil phase part.

(Classifying Apparatus)

The following will describe a classifying apparatus used in Examples 5through 9 given below.

A classifying apparatus including an upper plate made of the foregoingglass and a lower plate made of the foregoing PTFE was used. Morespecifically, for an intermediate plate, used was a 12 μm-thick aluminumfoil having a 10-by-10 mm hollow. In addition, a distance between asupply port and an exit, provided on the upper plate, was set to be 5 mm(emulsion flow length of 5 mm; indicated with “1” in FIG. 3). Then, theclassifying apparatus was made up in the same manner as the classifyingapparatus used in Example 1.

In a classifying apparatus used in Example 9, a thickness of thealuminum foil (produced by Nilaco Corporation) is 5 μm. In a classifyingapparatus used in Example 10, a thickness of the aluminum foil is 12 μm.In a classifying apparatus used in Example 11, a thickness of thealuminum foil is 24 μm. Except for a thickness of the aluminum foil, theclassifying apparatuses have the same arrangement as the classifyingapparatus used in Example 5.

In classifying apparatuses used in Comparative Examples 2 and 3, theforegoing glass was used for their lower plates. Except for a materialof the lower plate, they have the same arrangement as the classifyingapparatus used in Example 5.

In classifying apparatuses used in Example 7 and Comparative Examples 2and 3, a micromixer was directly connected to the supply port of theclassifying apparatus. In Examples 8 through 11, an emulsion generatedby a micromixer was put in a syringe, and thereafter the emulsion wassupplied from the syringe to the classifying apparatus.

(Dynamic Contact Angle)

As to water, on glass and PTFE, in an oil (dodecane or octanol; organicsolvent contained in an emulsion to be measured), a static contactangle, a dynamic contact angle, and a dynamic retreat angle (dynamiccontact angle) were measured by means of a contact angle meter (producedby Kyowa Interface Science Co., Ltd.; CA-V). Measurement of the dynamiccontact angle was performed as follows: As illustrated in FIGS. 5(a) and5(b), images of (i) a contact angle of a liquid being wetted and spreadwhen the liquid was forced to drop from a needlepoint (dynamic advanceangle) and (ii) a contact angle of a liquid drawn up from a needlepoint(dynamic retreat angle) were captured in time series, and then analysiswas performed. A result of the analysis is shown in Table 2. TABLE 2 1.0wt % of Sodium Dodecyl Sulfate Dodecane Octanol Aqueous Solution SolidGlass PTFE Glass PTFE Glass PTFE θ 79° 152° 49° 140° θ ad 83° 160° 52°161° 10° 160° θ re  0° 160°  0° 125°  0° 160°θ: Static Contact Angleθ ad: Dynamic Advance Angleθ re: Dynamic Retreat Angle

Example 5

For production of an emulsion, water containing 1 wt % of sodium dodecylsulfate and dodecane were supplied to the micromixer of Example 1 at arate of 2 ml/min each. Next, for classification, by using a microsyringepump, a pre-produced emulsion was supplied at a rate of 0.3 ml/min tothe classifying apparatus 1 having the upper plate 2 made of glass, thelower plate 4 made of PTFE, and the intermediate plate 3 havinglaminated four sheets of aluminum foil to make a 48 μm-wide flow path(Type 2). A result of the classification is shown in Tables 3 and 4.

Example 6

Except for the intermediate plate 3 having laminated six sheets ofaluminum foil to make a 72 μm-wide flow path, classification wasperformed as in Example 5. A result of the classification is shown inTables 3 and 4.

Example 7

For production of an emulsion, water and dodecane were supplied to themicromixer used in Example 1 at rates of 2.7 ml/min and 0.3 ml/min,respectively.

Next, an outlet of the micromixer is connected through a silicon tube tothe supply port of the classifying apparatus. Then, for classification,the emulsion was supplied at a rate of 3.0 ml/min from the supply portto the classifying apparatus (Type1). A result of the classification isshown in Tables 3 and 4.

A graph of FIG. 11 shows droplet diameter distributions of (a) liquiddroplets contained in an emulsion before being classified and (b) liquiddroplets contained in a liquid obtained after classification. In FIG.11, a droplet diameter distribution after classification is shown by adotted line, and a droplet diameter distribution before classificationis shown by a solid line.

FIG. 12 shows a microscope image of a state of an emulsion before beingclassified. FIG. 13 shows a microscope image of a state of an emulsionafter being classified.

Example 8

For production of an emulsion, water and octanol were supplied to amicromixer (produced by Yamatake Corporation; YM-1) at rates of 20.0ml/min and 5.0 ml/min, respectively. Thereafter, the produced emulsionwas impounded in a syringe. Then, the emulsion was supplied at a rate of0.3 ml/min by using a pump. Except for these conditions, classificationof an emulsion was performed as in Example 7. A result of classificationis shown in Tables 3 and 4.

Comparative Example 2

Except for the use of a classifying apparatus including the lower platemade of a different material (lower plate: glass, upper plate: glass),classification of an emulsion was performed as in Example 7. A result ofclassification is shown in Tables 3 and 4.

A graph of FIG. 14 shows droplet diameter distributions of (a) liquiddroplets contained in an emulsion before being classified and (b) liquiddroplets contained in a liquid obtained after classification. In FIG.14, a droplet diameter distribution after classification is shown by adotted line, and a droplet diameter distribution before classificationis shown by a solid line.

Comparative Example 3

For production of an emulsion, water and dodecane were supplied to amicromixer (same as the micromixer used in the Example 7) at rates of5.4 ml/min and 0.6 ml/min, respectively. Thereafter, the producedemulsion was supplied at a rate of 6.0 ml/min to the classifyingapparatus. Except for these conditions, classification of an emulsionwas performed as in Comparative Example 2. A result of classification isshown in Tables 3 and 4.

A graph of FIG. 14 shows droplet diameter distributions of (a) liquiddroplets contained in an emulsion before being classified and (b) liquiddroplets contained in a liquid obtained after classification. In FIG.14, a droplet diameter distribution after classification is shown by adotted line, and a droplet diameter distribution before classificationis shown by a solid line.

Example 9

For production of an emulsion, 1.0 wt % of sodium dodecyl sulfateaqueous solution and dodecane were supplied to a micromixer (same as themicromixer used in the Example 7) at a rate of 2.0 ml/min each.Thereafter, for classification, the produced emulsion was supplied at arate of 0.3 ml/min to the classifying apparatus. A result ofclassification is shown in Tables 3 and 4.

Example 10

For production of an emulsion, 1.0 wt % of sodium dodecyl sulfateaqueous solution and dodecane were supplied to a micromixer (same as themicromixer used in the Example 7) at a rate of 2.0 ml/min each.Thereafter, for classification, the produced emulsion was supplied at arate of 0.3 ml/min to the classifying apparatus that is the same as theclassifying apparatus used in Example 7. A result of classification isshown in Tables 3 and 4.

Note that, a graph of FIG. 15 shows droplet diameter distributions of(a) liquid droplets contained in an emulsion before being classified and(b) liquid droplets contained in a liquid obtained after the emulsionwas flown to the classifying apparatuses respectively having a 5μm-depth flow path (Example 9) and a 12 μm-depth flow path (Example 10)(after classification).

Example 11

For production of an emulsion, 1.0 wt% of sodium dodecyl sulfate aqueoussolution and dodecane were supplied to a micromixer (same as themicromixer used in the Example 7) at a rate of 2.0 ml/min each.Thereafter, for classification, the produced emulsion was supplied at arate of 0.3 ml/min to the classifying apparatus (having a 24 μm-depthflow path). A result of classification is shown in Tables 3 and 4.Average Droplet Particle Diameter of Emulsion Flow Rate in Flow Rate inImmediately After Types of Continuous Dispersed Oil Phase Aqueous PhaseProduced by Mixer Supply to Mixer Phase Phase [ml/min] [ml/min] (μm)Device Example5 IMM 1.0 wt % of Dodecane 2.0 2.0 71.8 Type 2 Example6Sodium 71.8 Dodecyl Sulfate Aqueous Solution Example7 IMM Water Dodecane0.3 2.7 66.2 Type 1 Example8 YM-1 Water Octanol 5.0 20.0 11.5 Type 2Example9 IMM 1.0 wt % of Dodecane 2.0 2.0 71.8 Type 2 Example10 SodiumDodecyl Sulfate Aqueous Solution Comparative IMM Water Dodecane 0.3 2.766.2 Type 1 Example2 Comparative 0.6 5.4 55.6 Example3 Average DropletParticle Diameter Rate of of Emulsion Supply to Residence Flow PathWhich Passed Material of Material of Device Time Depth of Device ThroughFlow Upper Surface Lower Surface [ml/min] [sec] [μm] Path (μm) of Deviceof Device Example5 0.3 0.48 48 47.0 Glass PTFE Example6 0.72 72 59.8Example7 3.0 0.012 12 Close to Zero Example8 0.3 0.120 12 2.8 Example90.3 0.05 5 3.9 Example10 0.3 0.120 12 7.9 Comparative 3.0 0.012 12 67.5Glass Glass Example2 Comparative 6.0 0.006 55.4 Example3

TABLE 4 Before Classified After Classified Percentage of Percentage ofDroplets Having Droplets Having Average Droplet Diameter Not AverageDroplet Diameter Not Particle Less Than Flow Flow Path Particle LessThan Flow Diameter (μm) Path Depth Depth (μm) Diameter (μm) Path DepthExample5 71.84 80.3 48 47.00 37.77 Example6 71.84 43.1 72 59.81 24.21Example7 66.2 99.4 12 Impossible to Measure due to Extreme Paucity ofDroplets Example8 11.5 49.8 12 2.84 0.5 Example9 85.9 99.5 5 3.85 13.1Example10 85.9 91.0 12 7.89 13.7 Comparative 66.2 99.4 12 67.5 99.0Example2 Comparative 55.6 98.7 12 55.4 97.9 Example3

Out of the above results shown in Tables 3 and 4, Table 5 shows theresults of the classifications performed in such a manner that theemulsions produced by supplying 1.0 wt % of sodium dodecyl sulfateaqueous solution and dodecane to a micromixer (same as the micromixerused in the Example 7) at a rate of 2.0 ml/min each were supplied at arate of 0.3 ml/min respectively to the classifying apparatuses havingdifferent flow path depths. TABLE 5 Before Classified After ClassifiedPercentage of Percentage of Droplets Having Droplets Having AverageDroplet Diameter Not Average Droplet Diameter Not Flow Path ParticleLess Than Flow Particle Less Than Flow Depth (μm) Diameter (μm) PathDepth Diameter (μm) Path Depth Example9 5 71.84 99.5 3.85 13.1 Example1012 71.84 99.0 6.53 6.0 Example11 24 71.84 98.2 15.45 2.1 Example5 4871.84 80.3 47.00 37.8 Example6 72 71.84 43.1 59.81 24.2

Example 12

For production of an emulsion, 1.0 wt % of sodium dodecyl sulfateaqueous solution and dodecane were supplied to a micromixer (same as themicromixer used in the Example 7) at a rate of 2.0 ml/min each.Thereafter, for classification of the produced emulsion, the emulsionwas supplied at a rate of 1.0 ml/min to the classifying apparatus usedin Example 10.

Example 13

For production of an emulsion, 1.0 wt % of sodium dodecyl sulfateaqueous solution and dodecane were supplied to a micromixer (same as themicromixer used in the Example 7) at a rate of 2.0 ml/min each.Thereafter, for classification of the produced emulsion, the emulsionwas supplied at a rate of 0.6 ml/min to the classifying apparatus usedin Example

Results of classifications (Examples 10, 12, and 13) performed under thesame conditions, except for a supply rate, are shown in Table 6. TABLE 6Before Classified After Classified Percentage of Percentage of DropletsHaving Droplets Having Average Droplet Diameter Not Average DropletDiameter Not Flow Rate Flow Path Particle Less Than Flow Particle LessThan Flow (ml/min) Depth (μm) Diameter (μm) Path Depth Diameter (μm)Path Depth Example12 1.0 12 71.84 99.0 31.28 51.3 Example13 0.6 12 71.8499.0 18.14 26.0 Example10 0.3 12 71.84 99.0 6.53 6.0

From the above results, it is clear that classification can be performedfavorably in an arrangement where the flow path depth is smaller thanthe largest diameter of liquid droplets contained in the emulsion, andat least a part of walls forming the flow path is made of a dropletaffinity material having an affinity with the liquid droplets.

Even when an emulsion containing a surfactant is used, a classifyingapparatus according to the present invention can favorably classify itsliquid droplets.

As described above, a classifying apparatus according to the presentinvention has a flow path having a desired depth or width smaller thanthe largest diameter in liquid droplets contained in an emulsion,wherein at least a part of the flow path is made of a material havingaffinity with the liquid droplets.

When the emulsion passes through the flow path, the liquid dropletslarger than a desired depth or width (hereinafter referred to as thesmallest length) smaller than the largest diameter in liquid dropletscontained in the emulsion in the flow path, among the liquid dropletscontained in the emulsion, deform so as to fit in the smallest length,and the liquid droplets are wetted on a material having an affinity withthe liquid droplets (hereinafter it may be referred to as dropletaffinity material). Then, when the emulsion is continuously supplied tothe flow path, there occurs a difference in relative velocity between adispersion medium flowing through the flow path and the liquid droplets.This is because the liquid droplets are wetted on the droplet affinitymaterial, and the dispersion medium resists being wetted on the dropletaffinity material. Then, if liquid droplets on the upstream of the flowpath are smaller in size than liquid droplets on the downstream of theflow path, the liquid droplets on the upstream catch up with the liquiddroplets on the downstream. At this moment, the liquid droplets arewetted on the droplet affinity material, and therefore coalesce withother liquid droplets by acting to decrease their surface areas fortheir stabilities. This causes coalescence of the liquid droplets largerthan the smallest length of the flow path by passing through the flowpath. On the other hand, liquid droplets smaller than the smallestlength of the flow path pass without being wetted on the dropletaffinity material and therefore do not coalesce with other liquiddroplets. Thus, the smaller liquid droplets keep their shape even afterhaving passed through the flow path.

According to the above arrangement, the liquid droplets larger than thesmallest length can be formed to a larger liquid droplet (made coalescedwith each other) in such a manner that the liquid droplets contained inthe emulsion are caused to pass through the flow path having thesmallest length, more specifically, the liquid droplets contained in theemulsion are caused to pass in a wetted state through the flow path.With this, the liquid droplets can coalesce with each other to form acontinuous phase, and then separate from the emulsion. Further, theliquid droplets smaller than the smallest length keep as they are.

That is, with the above arrangement, it is possible to reliably flow theliquid droplets contained in the emulsion through the flow path havingthe smallest length. Thus, it is possible to classify the liquiddroplets contained in the emulsion so as to obtain liquid dropletshaving a desired diameter or smaller.

Further, a classifying apparatus of the present invention is morepreferably such that the depth or width is equal to or less than avolume average diameter of the droplets contained in the emulsion.

According to the above arrangement, it is possible to obtain liquiddroplets diameter distribution of which is more uniform, by making thedepth or width equal to or less than the volume average diameter of thedroplets contained in the emulsion.

Still further, a classifying apparatus of the present invention is morepreferably such that the flow path is the one having length capable ofexisting in the flow path at least two droplets contained in theemulsion.

According to the above arrangement, at least two droplets contained inthe emulsion can exist in the flow path. Thus, the liquid droplets inthe flow path can be more reliably made coalesced with each other.

Yet further, a classifying apparatus of the present invention is morepreferably such that a part of walls forming the flow path is furthermade of a material having more affinity with dispersion medium(hereinafter it may be referred to as droplet non-affinity material),rather than with the droplets contained in the emulsion.

The droplet non-affinity material is a material on which the dispersionmedium of the emulsion is more likely to be wetted. With the abovearrangement, a part of the flow path made of the droplet non-affinitymaterial, which is more likely to be wet with the dispersion medium ofthe emulsion, can reduce a pressure drop that occurs when the emulsionis supplied to the flow path.

Further, a classifying apparatus of the present invention is morepreferably such that the emulsion is oil-in-water type emulsion, andwherein the droplet affinity material is a material having affinity withoil and having a dynamic contact angle of water in oil of 90 degree ormore.

According to the above arrangement, as the droplet affinity material, alipophilic material having a dynamic contact angle of water in oil of 90degree or more is used. Therefore, in a case where an oil-in-water typeemulsion is used as the emulsion, the liquid droplets contained in theoil-in-water type emulsion flowing in the flow path can be reliablywetted thereon. This can realize more excellent classification of theoil-in-water type emulsion. Note that, the “oil” is the same as acomponent (organic solvent) of oil droplets (liquid droplets) containedin the foregoing emulsion.

Still further, a classifying apparatus of the present invention is morepreferably such that the material having affinity with oil is fluorineresin.

Fluorine resin is superior in chemical resistance. Therefore, accordingto the above arrangement, with the use of fluorine resin as thelipophilic material, it is possible to favorably classify even anemulsion having a high reactivity with respect to a material making upthe flow path, for example.

Yet further, a classifying apparatus of the present invention is morepreferably such that the emulsion is water-in-oil type emulsion, andwherein the droplet affinity material is a material having the dynamiccontact angle of water in oil of less than 90 degree.

According to the above arrangement, as the droplet affinity material, alipophilic material having a dynamic contact angle of water in oil ofless than 90 degree is used. Therefore, in a case where a water-in-oiltype emulsion is used as the emulsion, the liquid droplets contained inthe water-in-oil type emulsion flowing in the flow path can be reliablywetted thereon. This can realize more excellent classification of theoil-in-water type emulsion. Note that, the “oil” is the same as acomponent (organic solvent) of liquids making up the foregoing emulsion.

Further, a classifying apparatus of the present invention is morepreferably such that the shape of cross section of the flow path isrectangular, and the smallest length in the cross section is smallerthan the largest diameter of the liquid droplets contained in theemulsion and the largest length in the cross section is ten times ormore as large as the smallest length in the cross section.

According to the above arrangement, the shape of the cross section ofthe flow path is rectangular, and the smallest (shortest) length (depthor width) in the cross section is smaller than the largest diameter ofthe liquid droplets contained in the emulsion. In addition, the largestlength in the cross section is ten times or more as large as thesmallest length in the cross section. With this arrangement, it ispossible to more easily deform liquid droplets contained in the emulsionwhen the liquid droplets pass through the flow path. That is, the aboveflow path allows the liquid droplets contained in the emulsion to moreeasily deform to fit in the smallest length of the flow path, and toescape to a wide space, as compared with a flow path being circular incross section and having a diameter equal to or smaller than the largestdiameter of the liquid droplets, for example. This can realize a smallerpressure drop that occurs when the emulsion is supplied to the flowpath. As compared with the flow path being circular in cross section,the above flow path can have a larger cross-sectional area, therebyflowing more emulsion through the flow path. This increasesproductivity.

Still further, a classifying apparatus of the present invention is morepreferably such that the walls forming the flow path contain at leasttwo sheets of plate materials and the two sheets are separated less thanthe largest diameter of the liquid droplets contained in the emulsion.

According to the above arrangement, a part of walls forming the flowpath is realized by plate materials. Thus, it is possible to more easilyform the flow path.

Yet further, a classifying apparatus of the present invention is morepreferably such that the emulsion is the one obtained by mixing emulsionmaterials in a micromixer.

The emulsion generated by mixing of the above material by means of amicromixer contains extremely small droplets. Generally, it is believeddifficult that extremely small liquid droplets coalesce with each otherfor their high stability. However, the above arrangement can realize afavorable coalescence even with the use of the emulsion having extremelysmall liquid droplets, which is generated by a micromixer.

Further, a classifying apparatus of the present invention is morepreferably such that the flow path has an exit discharging the emulsion,and a liquid separating apparatus is connected to the exit.

According to the above arrangement, the liquid separating apparatus(settler) is provided at the emulsion exit of the flow path. Thisenables a continuous and prompt separation of a classified emulsion.

Still further, a classifying apparatus of the present invention is morepreferably such that the apparatus has at least two flow paths.

According to the above arrangement, the apparatus has at least two flowpaths. This enables more emulsion to be classified at once.

As described above, a method for classifying emulsion of the presentinvention includes passing emulsion through a flow path in an apparatusfor classifying emulsion, wherein the apparatus has a flow path having adesired depth or width smaller than the largest diameter in liquiddroplets contained in the emulsion, and wherein at least a part of wallsforming the flow path is made of a material having affinity with theliquid droplets.

According to the above arrangement, the liquid droplets larger than thesmallest length can be formed to a larger liquid droplet (made coalescedwith each other) in such a manner that the liquid droplets contained inthe emulsion are caused to pass through the flow path having thesmallest length, more specifically, the liquid droplets contained in theemulsion are caused to pass in a wetted state through the flow path.Further, liquid droplets smaller than the smallest length keep as theyare.

That is, with the above arrangement, it is possible to reliably flow theliquid droplets contained in the emulsion through the flow path havingthe smallest length. Therefore, the liquid droplets larger than thesmallest length can coalesce with each other to form a continuous phase,and then separate from the emulsion. Thus, it is possible to classifythe liquid droplets contained in the emulsion so as to obtain liquiddroplets having a desired diameter or smaller.

A method for classifying emulsion of the present invention is morepreferably such that residence time of said emulsion in the flow pathranges from 0.001 to 10 seconds.

The above arrangement enables more reliable classification of the liquiddroplets contained in the emulsion.

A method for demulsifying emulsion of the present invention includespassing emulsion through a flow path in an apparatus for classifyingemulsion and phase-separating the passed liquid, wherein the apparatushas a flow path having a desired depth or width smaller than the largestdiameter in liquid droplets contained in the emulsion, and wherein atleast a part of walls forming the flow path is made of a material havingaffinity with the liquid droplets.

According to the above arrangement, the liquid droplets larger than thesmallest length can be formed to a larger liquid droplet (made coalescedwith each other) in such a manner that the liquid droplets contained inthe emulsion are caused to pass through the flow path having thesmallest length, more specifically, the liquid droplets contained in theemulsion are caused to pass in a wetted state through the flow path.Thus, it is possible to easily phase-separate the emulsion fordemulsification.

Specific embodiments or examples implemented in the description of thebest mode for carrying out the invention only show technical features ofthe present invention and are not intended to limit the scope of theinvention. Variations can be effected within the spirit of the presentinvention and the scope of the following claims.

INDUSTRIAL APPLICABILITY

A classifying apparatus according to the present invention has favorableapplications including obtaining of tiny liquid droplets byclassification performed in such a manner that large liquid droplets inan emulsion having liquid particles (liquid droplets) of differentparticle diameters (droplet diameters) are made coalesced with eachother.

1. An apparatus for classifying emulsion which has a flow path having adesired depth or width smaller than the largest diameter in liquiddroplets contained in the emulsion, wherein at least a part of wallsforming the flow path is made of a material having affinity with theliquid droplets.
 2. The apparatus according to claim 1, wherein thedepth or width is equal to or less than a volume average diameter of thedroplets contained in the emulsion.
 3. The apparatus according to claim1, wherein the flow path is the one having length capable of existing inthe flow path at least two droplets contained in the emulsion.
 4. Theapparatus according to claim 1, wherein a part of walls forming the flowpath is further made of a material having more affinity with dispersionmedium.
 5. The apparatus according to claim 1, wherein the emulsion isoil-in-water type emulsion, and wherein the material having affinitywith the liquid droplets is a material having affinity with oil andhaving a dynamic contact angle of water in oil of 90 degree or more. 6.The apparatus according to claim 5, wherein the material having affinitywith oil is fluorine resin.
 7. The apparatus according to claim 1,wherein the emulsion is water-in-oil type emulsion, and wherein thematerial having affinity with the liquid droplets is a material havingthe dynamic contact angle of water in oil of less than 90 degree.
 8. Theapparatus according to claim 1, wherein the shape of cross section ofthe flow path is rectangular, and wherein the smallest length in thecross section is smaller than the largest diameter of the liquiddroplets contained in the emulsion and the largest length in the crosssection is ten times or more as large as the smallest length in thecross section.
 9. The apparatus according to claim 1, wherein the wallsforming the flow path contain at least two sheets of plate materials andthe two sheets are separated less than the largest diameter of theliquid droplets contained in the emulsion.
 10. The apparatus accordingto claim 1, wherein the emulsion is the one obtained by mixing emulsionmaterials in a micromixer.
 11. The apparatus according to claim 1,wherein the flow path has an exit discharging the emulsion, and a liquidseparating apparatus is connected to the exit.
 12. The apparatusaccording to claim 1, wherein the apparatus has at least two flow paths.13. A method for classifying emulsion which comprises passing emulsionthrough a flow path in an apparatus for classifying emulsion, whereinthe apparatus has a flow path having a desired depth or width smallerthan the largest diameter in liquid droplets contained in the emulsion,and wherein at least a part of walls forming the flow path is made of amaterial having affinity with the liquid droplets.
 14. The methodaccording to claim 13, wherein residence time of said emulsion in theflow path is from 0.001 to 10 seconds.
 15. A method for demulsifyingemulsion which comprises passing emulsion through a flow path in anapparatus for classifying emulsion and phase-separating the passedliquid, wherein the apparatus has a flow path having a desired depth orwidth smaller than the largest diameter in liquid droplets contained inthe emulsion, and wherein at least a part of walls forming the flow pathis made of a material having affinity with the liquid droplets.